I'm confused about coral/carbonates in a planted tank.

[DragonFish71]

I forgot to add that plants won't grow in brackish water and most won't grow in a tank high in GH/PH which is what coral sand and gravel would make it.

Actually, my plants are growing insanely well in my BW tank.

There are certain types that adapt, java ferns and moss, vals, some swords, anubias, tiger lotus, marimo balls, banana plants, water lettuce, salvinia, ludwigia repens etc.

The trick is to start it fresh and slowly raise the salinity to the SG the fish require. I did this while cycling. I use reef salt for the calcium and minerals.

Here's some links that helped me

BracPlants

PlantGeek.net - Plant Guide

Starting a Brackish Aquarium, what you need and what you can keep.